Study Achieves A New Record Fiber QKD Transmission Distance of Over 509 km

According to a new study published in Physical Review Letters, researchers have achieved a new record quantum key distribution (QKD) transmission distance of over 509 kilometers. Phys.Org reports: "Using the sending-or-not-sending twin-field (SNS-TF) protocol, we realized secure quantum key distribution (QKD) over 509 km, which is a new record secure distance in QKD over fiber," Qiang Zhang, one of the researchers who carried out the study, told Phys.org. "One of the important objectives of our study was to successfully break the absolute key-rate limit of repeater-less QKD, with any measurement device." The SNS-TF protocol was developed and introduced in a previous research effort by some of the researchers who wrote the recent paper. In previous studies, the protocol proved to be highly advantageous for QKD applications, particularly for achieving long distance transmission.

In their recent work, Zhang and his colleagues implemented the SNS-TF QKD protocol by eliciting a single-photon level, first-order interference between two independent lasers. These two independent lasers were combined with a remote frequency locking technique, ultimately enabling QKD transmission over unparalleled distances. In their experiments, the researchers also used superconducting single-photon detectors with high count rate and detection efficiencies. Using their SNS-TF approach, the researchers achieved a secure key rate at 509 km, over seven times higher than the relative repeaterless bound QKD, and with the same detection loss. Remarkably, the key rate they achieved is also higher than that achieved by more traditional QKD protocols running on a perfect repeaterless QKD device.

Great

[matthiashj]

With this technology I can perhaps get decent speed in my childrenâ(TM)s room 10m from the router.

509 km!

[93 Escort Wagon]

And here we're so worried about coronavirus possibly traversing 2 meters...

Re:

[arglebargle_xiv]

Amazing achievement isn't it. Now if they can extend it by another 39,566km they'll have achieved the same as Diffie-Hellman key agreement from 1976.

Re:

[AmiMoJo]

DH relies on an eavesdropper not being able to recover the private key. These days it may not be safe to rely on that, and in the future there is a good possibility that at least governments and large corporations will be able to crack it in reasonable time.

With QKD any interception is detectable.

Re:

[arglebargle_xiv]

Not necessarily, there have been various attacks on it demonstrated in the past, and in for DH you just need good security practice to protect the key, the same that you'd use to protect the comms going over the channel, which is what the attacker will be targeting in any case, not the crypto. In any case having a staggeringly expensive means of achieving short-distance key exchange when you can do it virtually for free over any distance isn't notably useful except (a) as a gee-whiz demonstrator and (b) to

Which institute? Where?

[khchung]

Isn't it customary to include the institute the researchers, or at least the leader, work for?

For example, if this was done in MIT, the headline most likely would be "MIT achieved new record ...."

Same detection loss

[Calydor]

So ... 100%?

Compare to what was done before

[k6mfw]

Maybe going OT but interesting I was watching this last night about the first trans Atlantic telephone cable. This cable had to use latest technologies developed by Bell Labs of miniaturized vacuum tube repeaters every 200 miles. https://www.youtube.com/watch?... [youtube.com]